ionospheric ducting

Ionospheric ducting
is a term used to describe how fragments of radio broadcasts or
walkie-talkie communications can travel thousands of miles by
occurring in electronic layers of the ionosphere that create
small “ducts” that allow them to travel great distances. The observational
evidence for long-range propagation of high-frequency radio
signals began to accumulate in 1926 when transatlantic
communication links had been established. In 1927, signals were
detected that had propagated over large distances or circled the
Earth with little attenuation.*

According to Jurgen Graff, a former engineer at
Telefunken,
"a taxi
driver communication in New York could suddenly be monitored for a
couple of minutes in Europe. After a few minutes the ducts
collapse and the phenomenon disappears." (Roach, p. 188).

It is likely that
some of the recordings put forth as evidence of spirits
communicating from the afterlife are due to ionospheric ducting.